tipc: deal with return value of tipc_conn_new callback

Once tipc_conn_new() returns NULL, the connection should be shut
down immediately, otherwise, oops may happen due to the NULL pointer.

Signed-off-by: Ying Xue <ying.xue@windriver.com>
Reviewed-by: Jon Maloy <jon.maloy@ericson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tipc/server.c

@@ -309,6 +309,10 @@ static int tipc_accept_from_sock(struct tipc_conn *con)
 
 	/* Notify that new connection is incoming */
 	newcon->usr_data = s->tipc_conn_new(newcon->conid);
+	if (!newcon->usr_data) {
+		sock_release(newsock);
+		return -ENOMEM;
+	}
 
 	/* Wake up receive process in case of 'SYN+' message */
 	newsock->sk->sk_data_ready(newsock->sk);